Duplex telegraph system



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DUPLEX TELEGRAPH SYS TEM n QQ 'l Filed OCT,- 15. 1930 2 Sheets-511881 l Twig @www DUPLEX 'TELEGRAPH SYSTEM Filed Oct. 13, 1930 2 Sheets-Sheet 2 Alg AZZ

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R. T@STER, 0F EDGE, NEW JERSEY, ASSEGNGR T0 THE WESTERN UNIQN TELEGRAPE CGMLPAEQY, 0?? NEW YORK, El'. Y., il. CBIEORTION QF NEW YORK BUPLE; TELEGRALJE SYSTEM application n le'd @ctober 18, 1230.. Serial No. 488,422.

.This invention relates to duplex telegraph systems, and more particularly to an arrangeinent for repeating or relaying telegraph signal in duplex system. Y

An object of my invention is to devise a relay or repeating system employing thyratron relays for repeating telegraphic signals in a duplex system. l

ln a duplex telegraph circuit each end ci" the duplened line is subjected to battery p0- tential at all times. his potential may be changed at will from positive izo-negative or vice versa, but the potential supplied at either end of the line must not aect the receiving equipment .at that end. ln this invention l propose to employ 'at an intermedia-te or relay station thyratron relays for repeating telegraph'ic signals between two sections of a duplexed line. ln such a repeater, the operal tion must be the same as at any terminal station, that is, battery potential must be applied at each end ci both line sections at all times, and this potential impressed upon one line section must be varied in polarity in accordance with incoming signals transmitted over the other line section.

My invention is illustrated in the accompanying dra-Wings in which t; i

lligure l is a circuit diagram ofone form orn the invention, Figure l-A is a circuit diagram illustrating a modification of the arrangement shown in Figure l, and

Figure 2 is a circuit diagram illustrating another iorm ot' my invention employing a single source of operating potential for all thyratron relays at the relay station.

Referring to Figure l, A and B are terminal stations located at the ends of a duplexed telegraph line divided into two sections indicated as lil and L2 connected by an intermediate relay station indicated generallyat C. Each terminal station is provided with suitable transmitting apparatusfor impressing positive a-nd negative battery upon the line sections in accordance with desired telegraphic messages. The terminal stations are also provided with balancing artificial lines to prevent the currents transmitted from each station from aecting the receiving apparatus at that station.

At the repeater station line section Ll is terminated in a balanced duplex bridge arrangement comprising resistance arms Rl and R2, artificial line ALS, and a trans- 4 former Tl connected across arms Rl and R2. Line section L2 is likewise terminated at repeaterstation C in a bridge arrangement comprising resistance arms R3, R4, artificial line Alle, and transformer T2 connected across arms R3 and Re. rl`he apex of the bridge for line lll is connected to ground through resistance R5 and R6, and the apex of bridge for line L2 is connected to ground through -resistances R7 and R8. 'A thyratron relay l has its cathode connected to the apex of the bridge of line Ll, and its plate circuit includes resistance R5, battery B2 and resistance R9.' A second thyratron relay 2 has its cathode connected to ground, and its anode circuit includes resistance R6, battery B2 and resistance R10. A condenser C2 is connected between the anode elements or" relays l and 2 across resistances R9 and R10. lin a similar manner, the cathode of a thyratron tube lA is connected to the apex ci the bridge' o-.line L2, and its plate circuits include a resistance R7, battery Bl, and resistance Ril. Also, the cathode of a fourth thyratron relay A2 is connected to ground, and its anode circuit includes a resistance R8, battery Bl and resistance R12. A condenser Cl is connected between the anode elements of tubes 1A and 2A.

The outer terminals of the secondary of transformer Tl are connected respectively to the grid or control elements of relay tubes 1A and 2A. The midpoint of the secondary Winding of this transformer is connected to the negative side of plate battery Bl, and this connection includes a resistance R13 and .a stabilizing battery B3. Likewise, Vthe outer terminals of the secondary of transformerTQ are connected respectively to the grid elements of relays 1 and 2, and the midpoint of this secondary winding is connected to the-negative terminal of battery B2, with a resistance element R14 and a stabilizing battery B4 included in this connection.

It is characteristic of thyratron tubes to operate When the grids become positive with respect to the filaments, and to remain operated until the plate circuit is broken or the platepotential is reduced to a point below that required to start the tube. The bat teries B3 and B4 are provided for the purppse of maintaining the grids of the tube low the operating voltage to prevent selfoperation of the tubes when no signals are vbeing received.

Operation of Figure 1 is as follows: Suppose stations A and B are transmitting a positive signal or impulse. The signal from station A is received at the repeater station C over line L1 for retransmission into line L2. The positive signal so received at the intermediate station from line L1 causes a difference of potential across the bridge of the duplex circuit and therefore energizes the primary Winding of the transformer T1 connected to line L1.

The secondary of the transformer T1 is so poled- `that a'. positive signal from the line excitin the rimary winding causes an induced M. in the secondary of the transformer in such a manner as to make the portion of the secondary associated with the grid of tube 1A positive with respect to the center tap of the transformery and the other side of the secondary winding (that connected to tube 2A) negative With respect to the center or mid-tap of the transformer. The mid-tap of the transformer in both cases is the grid return, hence the positive potential applied to the grid of tube 1A causes this tube to become operative and the negative potential prevents the operation of tube 2A.

When tube 1A is operated, a circuit is established from battery B1, resistance R11., plate and filament of tube 1A, resistance R7 to negative battery. At the same time a circuit is established from the filament of tube 1A to the apex of line L2 from whence it divides into two circuits for the normal duplex operation of a line. In either branch circuit the return is to ground at the intermediate station or at station B from whence the return to battery is accomplished from ground, resistance R8 and battery B1. The signal from station A is in this manner repeated at the intermediate station into the apex of line 2 and transmitted to station B.

In a like manner the positive signal transmitted from station B operates the transformer T2 and energizes the grid of tube 1, thereby causing a positive potential to be applied to the apex of line L1 at the intermediate station, and the signal so supplied is thus repeated to station A.

Suppose station A next sends a negative signal to station B. This signal is received at the intermediate station over line L1 and energizes transformer T1 in the opposite distations.

rection, thereby causing the grid of tube 2A to become positive and the grid of tube 1A negative with respect to the grid return or mid-tap of the transformer. 'l'ube 2A therefore is operated, and in so doing it causes a drop in the potential applied to the plate of tube 1A by the action of condenser C1 and the resistance R11 and R12. Tube 1A '1s therefore stopped. The operation of tube 2A takes place in the circuit from battery Bl, resistance R12, plate and filament of tube 2A, resistance R8 to battery B1. A second cir* cuit is energized from filament of tube 2A to ground through line L2 by means of the ground connection at station B, resistance n to apex of line`,'also ground at the intermediate station, artificial line ALl, resistance R4 to apex of line thence to R7 to battery B1. This circuit causes a negative potential to be applied to the apex of the line due to the fact that the positive side of battery Bl has been connected to ground, and the return of the apex is to negative battery through resistance R7. l

The negative signal from station A is thus repeated into line L2 as long as tube 2A remains operated. The next positive signal will cause the operation of tube 1A which in turn stops tube 2A. In this manner signals from one line section are retransmitted by the tubes into the next line section.

In Figure 1-A I have shown an alternative method for connecting the grids of the thyratron tubes in place of the transformer T1 or T2 shown in Figure 1.

While the arrangement shown in Figure 1 is for bridge duplex operation, it will be understood that the differential duplex arrangement may be employed in which case the primary winding is inserted in place of resistances R1 and R2 (or R3 and R4) and the apex connection is made to mid-tap connection of the primary Winding.

Standard practice in the telegraph field is to use one battery as far as possible for the various circuits at any stations; also to ground the mid-point of the battery for grounded circuits or make the mid-point a common point for metallic circuits.

Figure 2 shows an arrangement in which only one battery is used for both halves of a repeater or a group of repeaters at the same It is understood that the receiving and retransmission -equipment and the necessary connections thereto associated with each line constitutes half of the repeater, thus operation in both directions requires a Whole repeater.

The battery connections of Figure 2 is so arranged that the same battery may be used either for thyratron tube transmission or for relay transmission which at present is the cor]nm'on method for repeating telegraph signa s.

The arrangement' shown in Figure 2 differs from that in Figure 1 in that tubes 2 and 2A do not serve to transmit signal impulses to the line sections, but these tubes serve only to stop the operation of tubes 1 and 1A respectively. Also tubes 1 and 1A operate to transmit only one polarity of signal impulses, and the opposite polarity is transmitted by battery B5 when tubes 1 and 1A are deenergized.

As will be seen from the drawing, tubes 1A and 2A are provided with separate secondary windings for energizing their grid circuits, and separate stabilizing batteries Ba and Bb, and also separate current limiting resistances Rc and Bal.v In alike manner separate transformer windings, stabilizing batteries and limiting resistances are provided for the grid circuits of tubes l and 2. The common energizing battery for' the system is formed of two sections B5 and B6, the midpoint of which is grounded. rThe apex of the bridge associated with line section L1 is connected to the ungrounded terminal of battery B5 through an' adjustable resistance Ra, and the apex of the bridge for line L2 is connected to the same battery terminal through an adjustable resistance Rb. These connections normally impress negative battery upon the apex points of both line sections. The apex of line L1 is also connected to the cathode of tube 1, and the apex of line L2 Vis likewise connected to the cathode of tube 1A. The anode elements of tubes 1 and 2 are connected to the positive terminal of battery B6 through resistances R9 and R10 respectively, and a condenser'C2 is connected between these anode elements. Likewise, the anode elements of tubes 1A and 2A are connected to the positive terminal of battery B6 through resistance elements R11 and R12, and condenser Cl is connected between the anode elements The cathode element of tube 2A is connected to ground 'through an adjustable resistance Re, and-the cathode element of tube 2 is connected to-ground through an adjustable resistance Rh. The function of variable resistances Re and Rh is to limit the current in the anode circuit of tubes 2A and 2 to a value suicient to cause the stopping of the other two tubes.

From an inspection of Figure 2 it will be seen that the operation or non-operation of vthyratron relays 2 and 2A will not aect the transmitted from station A to station B through the repeating station C.

When a negative s1gnal from station A is received at the intermediate station for retransmission to station B, the grid of tube 2A becomes. positive by the action of transformer T1 as explained in connection with Fig. 1. Tube 2A becomes operative due to the action of the potential of its grid as explained for the operation of thyratron tubes, and a circuit isestablished from battery B6, resistance R12, plate and filament of tube 2A, resistance Re to Ground and back to the split of the battery. l-urrent in this circuit causes a drop in potential across condenser Cl great enough to stop tube 1A if it is in operation.

lVhenever the tube 1A becomes non-operative, current Hows in the circuit from negative battery B5, resistance R?) into the a ex of line L2, to ground at station B, an to ground through resistance R4 and artificial line AL4 at the intermediate station and to the positive battery B5. Since the negative side of battery B5 is connected to the apex of line L2, the negative signal is sent into the apex of line L2, which is grounded to the positive side of battery B5.

When a positive signal' is received from station A, tube 1A becomes operative and in doing so stops tube 2A. The circuit is from ositive batter B6, resistance R11, plate and lament of tuge 1A, resistance R6, to negative battery B5; also from tube filament to apex of line L2, to ground at both stations B through line L2 or at the intermediate station through the articial line. The adjustment of resistance Rb is such that the apex of the line becomes of a positive potential great enough to force the same amount of current through the line in the opposite direction from that caused bythe negative battery B5 for the negative signal.- Due to the action of battery B6 and resistance Rb the apexpf the line is at a -higher potential than the midpoint of battery, hence a positive signal is supplied to the apex of the line.

I claim: 1. In a signaling system, a pair of line sections terminating in a' repeater station andeach provided with balanced transmitting and receiving circuits for duplex operation, means at the repeater station for'normally impressing current upon the transmitting circuit of each line section, and means includ-v ing a thyratron relay responsive to signals received over one line sectlon for reversing the polarity of the current applied to the other line section.

2. In a signaling system, a pair of line sec-4 tions tegminating` in a repeater station and each provided with balanced transmitting and receiving circuits for duplex operation, means at the repeater station for normally impressing current upon the transmitting circuit of each line section, and a thyratron 'impressing current upon relay associated with each section for reversing the polarity of the current applied to the other section in response to a received signal impulse of a polarity opposite to the polarity of the impressed current.

3. In a signaling system, a pair of line,sec tions terminating in a repeater station and each provided with balanced transmitting and receiving circuits for duplex operation, means at the repeater station for normally impressing current upon the transmitting circuit of each line section, means including a thyratron relay responsive to signals received over one line section for reversing the polarity of the current applied to the other line section, and means responsive to signal impulses of opposite polarity for deenergizing said thyratron relay.

4. In a signaling system, a pair of line sections terminating in a repeater station and each provided with balanced transmitting and receiving circuits for duplex operation, means at the repeater station for normally impressing current upon the transmitting circuit of each line section, a thyratron relay associated with each section for reversing the polarity of the current applied to the other section in response to a received signal impulse of a polarity opposite to the polarity of the impressed current, and means responsive to a received signal impulse of the same polarity as the impressed current to deenergize said thyratron relay.

5. In a signaling system, a pair of line sections terminating in a repeater station and each provided with balanced transmitting and receiving circuits for duplex operation, a pair of thyratron relays at said station and having their input circuits connected in opposed relation to the receiving circuit of one line section, and their output circuits included in opposed relation in the transmitting circuit of the other line section, and means associated with said relays for deenergizing one relay upon the energization of the other.

6. In a signaling system, a pair of line sections terminating in a repeater station and each provided with balanced transmitting and receiving circuits for duplex operation, a pair of thyratron relays associated with each line section at said repeater station, each pair of relayshaving their input' circuits connected in opposed relation to the receiving circuit of one line section and their output circuits included in opposed relation in the transmitting circuit of the other line section, and means associated with each pair of relays for deenergizing one relay of the pair upon energization of the other.

7 In a signaling system, a pair of line sections terminating in a repeater'station and each provided with balanced transmitting and receiving circuits for duplex operation, means at the repeater station 'for normally the transmitting 

